The United States has issued an anxious call for Egypt's leaders to stabilise
the country, after security forces killed scores of supporters of deposed
president Mohammed Morsi.

John Kerry, the secretary of state, spoke with two senior members ofEgypt's new military-installed cabinet, expressing his deep concern over the recent violence.

"This is a pivotal moment for Egypt," he said in a statement issued after their conversation.

"The United States calls on all of Egypt's leaders across the political spectrum to act immediately to help their country take a step back from the brink."

The US has struggled in its reaction to the turmoil gripping its Middle Eastern ally, with the Obama administration refusing to declare the military's ouster of the country's first democratically elected president a "coup".

By Washington's own rules, such a condemnation would for have forced President Obama to halt the more than $1 billion in annual military aid to the country.

Thousands of supporters of Mr Morsi gathered at Rabaa al-Adawia mosque in northern Cairo on Sunday, where, just 24 hours earlier, more than 70 Brotherhood supporters were killed in a fierce street battle with security forces.

The police, along with armed men in plain clothes used tear gas, birdshot and then fired live bullets into a swelling crowd of Morsi supporters in the early hours of Saturday morning.

The continuing protests by Muslim Brotherhood sympathisers are a show of defiance in response to the attack, with the demonstrators vowing to stay despite continued threats by the country's new military leaders to forcefully disperse them.

Mohamed Ibrahim, the interior minister said that "God willing" the vigil outside the Rabaa al-Adawia mosque would "soon be dealt with".

Mr Ibrahim refused to accept responsibility for Saturday's deaths, claiming that clashes had erupted between the Brotherhood protesters and local residents and police had only intervened with tear gas.

The government also claimed that the pro-Morsi protesters had been armed, and used guns against security forces. All of the deaths from the clashes however occurred on the Muslim Brotherhood side.

Chuck Hagel, the US defence secretary, also urged for the country's military to respect the people's right to protest. He spoke by telephone with Egyptian army chief General Abdel Fattah al-Sisi, who led the military overthrow of Morsi earlier this month.

Morsi's overthrow has polarised Egyptian society and has left the United States in the awkward position of being disliked by "both sides".

Anti-American slogans are common in both the protest camps, with Morsi's allies believing the US helped to orchestrate the coup, while the pro-army demonstrators dislike the US for accepting and working with the government of Mohammed Morsi.

At a pro-army demonstration at the presidential palace in Cairo on Friday night, security guards checked the passports of foreigners, purportedly because "we don't want any Americans here".

In Rabaa al-Adawia, at a press conference late on Saturday the Muslim Brotherhood called on the international community to condemn the bloodshed that had taken place and 'indict' Gen. Sisi for "war crimes".